Remediation of mixed pollutants with disparate properties is a major challenge necessitating action to develop effective treatment synergies. Chlorinated aliphatic hydrocarbons (CAHs) are high priority groundwater pollutants detected in the U.S. During the 20th century, CAHs, such as 1,1,1-trichloroethane (1,1,1-TCA) and trichloroethene (TCE), were widely used as “safety solvents” for weapon rinsing and pipeline degreasing at industrial and military facilities.
1,4-dioxane (dioxane), a cyclic ether, is an emerging water contaminant in the U. S and globally. Dioxane was added as a stabilizer to prevent degradation of chlorinated solvents, primarily 1,1,1-TCA, at an approximate volumetric ratio of 3.5%. This is of particular concern since dioxane is a probable human carcinogen and is subject to a stringent drinking water advisory level of 0.35 μg/L at the one to one million lifetime cancer risk. The remediation standard of dioxane has been reduced by various state and federal regulation agencies. The combination of extensive use, historical disposal, and persistent property of chlorinated solvents and dioxane has resulted in commingled plumes being prevalently formed in thousands of sites in the U.S. Many CAH-contaminated sites were considered “closed”, but were re-opened because dioxane was detected at those sites. Remediation of 1,4-dioxane and CAHs has become more urgent and relevant.